The server defines the NotPrimaryError category as:

• InterruptedDueToReplStateChange
• NotMasterOrSecondary
• PrimarySteppedDown
• NotMaster
• NotMasterNoSlaveOk

And the ShutdownError category as:

• InterruptedAtShutdown
• ShutdownInProgress

https://github.com/mongodb/mongo/blob/r4.9.0-alpha/src/mongo/base/error_codes.yml#L10

The SDAM spec however defines "not master" as:

• NotMaster
• NotMasterNoSlaveOk

And "node is recovering" as:

• InterruptedAtShutdown
• InterruptedDueToReplStateChange
• NotMasterOrSecondary
• PrimarySteppedDown
• ShutdownInProgress

I propose that we change SDAM's definitions to match the server's and rename "not master" and "node is recovering" to NotPrimaryError and ShutdownError respectively. This change will also allow us to replace the SDAM "node is shutting down" error with ShutdownError.